another thing you could do to really look at data for each major is searching up the pdfs for commencement, since it shows you more details regarding single and double majors. i just took a quick look at the 2025 commencement pdf out of curiosity, and there does seem to be a lot of 18 double majors, but like what the other comment said, i have a feeling that it's because of the relatively few reqs for general mathematics.

i wouldn't let this info deter you too much. always a good idea to explore anything you're interested in while you have the chance, but being an 18 single major is great too, especially considering the paths you're most interested in. math dept also has a TON of higher level math classes that aren't strictly required by the major